scholarly journals Nd-Hf isotope geochemistry and lithogeochemistry of the Rambler Rhyolite, Ming VMS deposit, Baie Verte Peninsula, Newfoundland: evidence for slab melting and implications for VMS localization

2021 ◽  
Author(s):  
S J Piercey ◽  
J -L Pilote
Keyword(s):  
Rare Earth ◽  
Trace Element ◽  
Isotope Geochemistry ◽  
Primitive Mantle ◽  
Isotopic Data ◽  
Depleted Mantle ◽  
Element Enrichment ◽  
Felsic Volcanic ◽  
Magmatic History ◽  
Felsic Rocks

New high precision lithogeochemistry and Nd and Hf isotopic data were collected on felsic rocks of the Rambler Rhyolite formation from the Ming volcanogenic massive sulphide (VMS) deposit, Baie Verte Peninsula, Newfoundland. The Rambler Rhyolite formation consists of intermediate to felsic volcanic and volcaniclastic rocks with U-shaped primitive mantle normalized trace element patterns with negative Nb anomalies, light rare earth element-enrichment (high La/Sm), and distinctively positive Zr and Hf anomalies relative to surrounding middle rare earth elements (high Zr-Hf/Sm). The Rambler Rhyolite samples have epsilon-Ndt = -2.5 to -1.1 and epsilon-Hft = +3.6 to +6.6; depleted mantle model ages are TDM(Nd) = 1.3-1.5 Ga and TDM(Hf) = 0.9-1.1Ga. The decoupling of the Nd and Hf isotopic data is reflected in epsilon-Hft isotopic data that lies above the mantle array in epsilon-Ndt -epsilon-Hft space with positive ?epsilon-Hft values (+2.3 to +6.2). These Hf-Nd isotopic attributes, and high Zr-Hf/Sm and U-shaped trace element patterns, are consistent with these rocks having formed as slab melts, consistent with previous studies. The association of these slab melt rocks with Au-bearing VMS mineralization, and their FI-FII trace element signatures that are similar to rhyolites in Au-rich VMS deposits in other belts (e.g., Abitibi), suggests that assuming that FI-FII felsic rocks are less prospective is invalid and highlights the importance of having an integrated, full understanding of the tectono-magmatic history of a given belt before assigning whether or not it is prospective for VMS mineralization.

Neodymium isotope geochemistry of felsic volcanic and intrusive rocks from the Yukon–Tanana Terrane in the Finlayson Lake Region, Yukon, Canada

2003 ◽  
Vol 40 (1) ◽  
pp. 77-97 ◽  
Author(s):  
Stephen J Piercey ◽  
James K Mortensen ◽  
Robert A Creaser
Keyword(s):  
Isotope Geochemistry ◽  
Volcanic Rocks ◽  
Lake Region ◽  
Volcanogenic Massive Sulphide ◽  
Depleted Mantle ◽  
Intrusive Rocks ◽  
Felsic Volcanic ◽  
Back Arc ◽  
Finlayson Lake ◽  
Felsic Rocks

Devonian–Mississippian felsic rocks from the Finlayson Lake region have variable geochemical and Nd isotopic characteristics that provide insights into the tectonic and metallogenic evolution of the Yukon–Tanana terrane (YTT), and the northern Cordillera. Late Devonian (~365–360 Ma) calc-alkaline and tholeiitic arc felsic rocks in the mafic-dominated Fire Lake unit yield εNd350 = –4.8 and +0.1, respectively, and have 1.49–1.94 Ga depleted mantle model ages (TDM). Devonian–Mississippian (~360–356 Ma) felsic volcanic (Kudz Ze Kayah unit, Wolverine succession) and intrusive rocks (Grass Lakes suite) associated with volcanogenic massive sulphide (VMS) deposits have εNd350 = –7.8 to –9.5 with TDM = 1.59–2.25 Ga. A granitoid sample from the Early Mississippian (~350–345 Ma) Simpson Range plutonic suite has εNd350 = –12.9 and TDM = 2.01 Ga, similar to previously reported values for this suite. The VMS-associated Grass Lakes suite of granitoids has higher high field strength element (HFSE) and rare-earth element (REE) contents, and higher Zr/Sc, Zr/TiO2, Nb/La, and Zr/La values relative to the Simpson Range plutonic suite; these geochemical features are similar to coeval VMS-associated felsic volcanic rocks in the Kudz Ze Kayah unit. The identification of similar HFSE–REE-enriched felsic volcanic and subvolcanic intrusive rocks may aid in delineating prospective regions for VMS mineralization in the YTT and other continental-margin arc to back-arc environments. The geochemical and Nd isotopic data for these YTT felsic rocks suggest that they reflect episodic mid-Paleozoic arc (Fire Lake unit; Simpson Range plutonic suite) and back-arc magmatism (Kudz Ze Kudz unit; Wolverine succession) built upon a transitional basement with variable, but significant, influence from evolved (Proterozoic) crustal materials.

scholarly journals Assessing the extent of local crust assimilation within the Flatreef, northern limb of the Bushveld Igneous Complex, using sulfur isotopes and trace element geochemistry

2020 ◽  
Author(s):  
Evan Keir-Sage ◽  
Matthew I. Leybourne ◽  
Pedro J. Jugo ◽  
Danie F. Grobler ◽  
Cédric C. Mayer
Keyword(s):  
Trace Element ◽  
Primitive Mantle ◽  
Trace Element Geochemistry ◽  
Isotopic Data ◽  
Igneous Complex ◽  
Merensky Reef ◽  
Northern Limb ◽  
Geochemical Parameters ◽  
Pge Mineralization ◽  
Bushveld Igneous Complex

Abstract The proximity to metasedimentary footwall rocks relative to platinum group element (PGE) mineralized intrusive rocks in the northern limb of the Bushveld Igneous Complex (BIC) has resulted in complex local contamination in the intrusions. To assess the extent of incorporation of non-magmatic material and its effects on PGE mineralization, major element, trace element, and S isotopic data were collected from drill core UMT094 on the Turfspruit farm, where core logging has shown that the mineralized Platreef, forming the Flatreef deposit, is located stratigraphically well above local sedimentary footwall rocks. The S isotopic data combined with whole rock geochemistry data (including CaO/Al2O3, (V/Ti)PM, (Ni/Cr)PM, S/Se, loss on ignition) were used to assess incorporation of a range of local footwall material. The δ34S data show a steady decrease from the footwall assimilation zone (δ34S typically + 8 to + 9‰, maximum 12‰) to near constant δ34S values (δ34S < + 4‰) below the main PGE reef. Similar values have been documented for the Merensky Reef in the eastern and western limbs of the BIC (δ34S ~ 0 to + 3.5‰). Other geochemical parameters, such as S/Se and CaO/Al2O3, also match the ranges documented for the Merensky Reef elsewhere in the BIC. In addition, parameters such as whole rock V/Ti, normalized to primitive mantle (V/Ti)PM, are shown to be useful indicators of contamination and the type of contaminant with 1 < (V/Ti)PM < 2 for uncontaminated magmatic units; [V/Ti]pm > 2 for shale assimilation; and [V/Ti]pm < 1 for carbonate assimilation. The results suggest that the main PGE mineralization in the Flatreef deposit formed without significant in situ contamination and that the primary mechanism of PGE mineralization in the Platreef at Turfspruit was no different than the mechanism that generated the Merensky Reef in the eastern and western limbs of the BIC.

Ophiolitic peridotites in Xigaze (Tibet): Constraints on modes of melt transport in the mantle

2021 ◽  
Author(s):  
Lingquan Zhao ◽  
Sumit Chakraborty ◽  
Hans-Peter Schertl
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Experimental Studies ◽  
Primitive Mantle ◽  
Melt Extraction ◽  
Chemical Signatures ◽  
Element Enrichment ◽  
Spider Diagrams ◽  
Incompatible Trace Elements ◽  
Reverse Zoning

&lt;p&gt;The Xigaze ophiolite (Tibet), which occurs in the central segment of the Yarlung Zangbo Suture Zone, exposes a complete portion of a mantle sequence that consists essentially of fresh as well as serpentinized peridotites. We studied a sequence beneath the crustal section that exposes fresh, Cpx-bearing harzburgites and dunites that are underlain by serpentinized Cpx-bearing harzburgites and dunites. The rocks at the bottom are crosscut by dykes that have undergone different degrees of rodingitization. The modal compositions of peridotite from both fresh and serpentinized sections plot in abyssal upper mantle fields, with clinopyroxene modes less than 5 vol. %. Although harzburgites and dunites indicate that melt has been lost relative to primitive mantle compositions, the trace element patterns carry signatures of enrichment in incompatible elements, such as (i) &amp;#8220;bowl-shaped&amp;#8221; patterns of trace elements in silicate-Earth normalized spider diagrams, (ii) positive anomalies in highly incompatible trace elements such as Rb, Th, U, Ta, and (iii) enrichment of LREE in the clinopyroxenes from dunites and harzburgites. These features are indicative of complex melt transfer processes and cannot be produced by simple melt extraction. Petrographic studies reveal that harzburgite and dunite contain interstitial polyphase aggregates of olivine + Cpx + spinel + Opx and olivine + Cpx + Spinel, respectively. Experimental studies (e.g. Morgan and Liang, 2003) suggest that these aggregates represent frozen melt-rich components, indicating that fertile melt was percolating through the depleted harzburgite &amp;#8211; dunite matrix. Presence of such &amp;#8220;melt pods&amp;#8221; would explain the trace element enrichment patterns of the bulk rock, as well as features such as reverse zoning (core: Cr, Fe&lt;sup&gt;2+&lt;/sup&gt; rich, rim: Al, Mg rich) of spinels in polyphase aggregates in fresh dunites. These results show that melt extraction from the mantle is not a single stage process, and that evidence of multiple melt pulses that propagated through a rock are preserved in the petrographic features as well as in the form of chemical signatures that indicate refertilization of initially depleted rocks.&lt;/p&gt;

Geochemistry of two metavolcanic arc suites from the Central Metasedimentary Belt of the Grenville Province, southeastern Ontario, Canada

1991 ◽  
Vol 28 (9) ◽  
pp. 1429-1443 ◽  
Author(s):  
Luc Harnois ◽  
John M. Moore
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Trace Element ◽  
Partial Melting ◽  
Volcanic Rocks ◽  
Parental Magma ◽  
Major Elements ◽  
Grenville Province ◽  
Element Abundances ◽  
Felsic Rocks

Samples of two subalkaline metavolcanic suites, the Tudor formation (ca. 1.28 Ga) and the overlying Kashwakamak formation, have been analysed for major elements and 27 trace elements (including rare-earth elements). The Tudor formation is tholeiitic and contains mainly basaltic flows, whereas the Kashwakamak formation is calc-alkaline and contains mainly andesitic rocks with minor felsic rocks. The succession has been regionally metamorphosed to upper greenschist – lower amphibolite facies. Trace-element abundances and ratios indicate that rocks of the Tudor and Kashwakamak formations are island-arc type. Geochemical modelling using rare-earth elements, Zr, Ti, and Y indicates that the Tudor volcanic rocks are not derived from a single parental magma through simple fractional crystallization. Equilibrium partial melting of a heterogeneous Proterozoic upper mantle can explain the trace-element abundances and ratios of Tudor formation volcanic rocks. The intermediate to felsic rocks of the Kashwakamak formation appear to have been derived from a separate partial melting event. The data are consistent with an origin of the arc either on oceanic crust or on thinned continental crust, and with accretion of the arc to a continental margin between the time of extrusion of Tudor volcanic rocks and that of Kashwakamak volcanic rocks.

Crustal assimilation in the Burnt Lake metavolcanics, Grenville Province, southeastern Ontario, and its tectonic significance

1997 ◽  
Vol 34 (9) ◽  
pp. 1272-1285 ◽  
Author(s):  
T. E. Smith ◽  
P. E. Holm ◽  
N. M. Dennison ◽  
M. J. Harris
Keyword(s):  
Rare Earth ◽  
Trace Element ◽  
Partial Melting ◽  
Continental Crust ◽  
Fractional Crystallization ◽  
Volcanic Rocks ◽  
Lake Area ◽  
Depleted Mantle ◽  
Mafic Magmas ◽  
Back Arc

Three intimately interbedded suites of volcanic rocks are identified geochemically in the Burnt Lake area of the Belmont Domain in the Central Metasedimentary Belt, and their petrogenesis is evaluated. The Burnt Lake back-arc tholeiitic suite comprises basalts similar in trace element signature to tholeiitic basalts emplaced in back-arc basins formed in continental crust. The Burnt Lake continental tholeiitic suite comprises basalts and andésites similar in trace element composition to continental tholeiitic sequences. The Burnt Lake felsic pyroclastic suite comprises rhyolitic pyroclastics having major and trace element compositions that suggest that they were derived from crustal melts. Rare earth element models suggest that the Burnt Lake back-arc tholeiitic rocks were formed by fractional crystallization of mafic magmas derived by approximately 5% partial melting of an amphibole-bearing depleted mantle, enriched in light rare earth elements by a subduction component. The modelling also suggests that the Burnt Lake continental tholeiitic rocks were formed by contamination – fractional crystallization of mixtures of mafic magmas, derived by ~3% partial melting of the subduction-modified source, and rhyolitic crustal melts. These models are consistent with the suggestion that the Belmont Domain of the Central Metasedimentary Belt formed as a back-arc basin by attenuation of preexisting continental crust above a westerly dipping subduction zone.

The nature of Triassic extension-related magmatism in Greece: evidence from Nd and Pb isotope geochemistry

1998 ◽  
Vol 135 (3) ◽  
pp. 331-348 ◽  
Author(s):  
GEORGIA PE-PIPER
Keyword(s):  
Isotope Geochemistry ◽  
Volcanic Rocks ◽  
Isotopic Data ◽  
Alkali Basalts ◽  
Aegean Area ◽  
Small Areas ◽  
Isotopic Compositions ◽  
Rock Types ◽  
Depleted Mantle ◽  
Subalkaline Basalt

The widespread Triassic volcanic rocks of Greece, dismembered during the Hellenide orogeny, are used to interpret the nature of Triassic rifting. Four assemblages of volcanic rocks are distinguished on geochemical criteria: (1) a predominant subalkaline basalt–andesite–dacite series with a high proportion of pyroclastic rocks; (2) minor shoshonites; (3) alkali basalt and (4) MORB. The stratigraphic and palaeogeographic distribution of these rock types is synthesized. New Pb and Nd isotopic data are used to discriminate between hypotheses suggesting that either subduction or extension was responsible for the Triassic volcanism. In the subalkaline basalt assemblage, εNd is negative with depleted mantle model ages >1.5 Ga. Pb isotopic compositions are mostly close to the very distinctive compositional field of Cenozoic extensional rocks of the Aegean area, with very high 207Pb/204Pb for relatively low 206Pb/204Pb ratios. These isotopic data confirm interpretations based on trace elements that subalkaline basalts were predominantly derived from melt-depleted peridotite in the sub-continental lithospheric mantle as a result of extension. Small areas of enriched hydrous mantle partially melted to yield shoshonitic magmas. Nd and Pb isotopic compositions of the alkali basalts are quite different from those in other rock types and suggest a HIMU mantle source component derived from a small plume, which also influenced MORB compositions. Distribution of these various rock types is used to constrain palaeogeographic reconstruction of Triassic micro-continental blocks.

scholarly journals Evidence of crustal contamination of mafic rocks associated with rapakivi rocks: an example from the Nordingrå complex, Central Sweden

2001 ◽  
Vol 138 (4) ◽  
pp. 371-386 ◽  
Author(s):  
ANDERS LINDH ◽  
ULF BERTIL ANDERSSON ◽  
THOMAS LUNDQVIST ◽  
STEFAN CLAESSON
Keyword(s):  
Trace Element ◽  
Crustal Contamination ◽  
Incompatible Trace Element ◽  
Primitive Mantle ◽  
Nd Isotope ◽  
East Central ◽  
Enriched Mantle ◽  
Depleted Mantle ◽  
Two Parameters ◽  
Isotope Analyses

Gabbro and leucogabbro are volumetrically important rocks in the Nordingrå rapakivi complex, East Central Sweden. Plagioclase, ortho- and clinopyroxenes, and olivine dominate the gabbro. Perthitic orthoclase and quartz are interstitial in relation to the major minerals. The present work is based on 232 major-element and a large number of trace element analyses together with 15 whole rock Sm–Nd isotope analyses of the Nordingrå gabbroic rocks. εNd(T) values are negative, −1.1 to −3.2; the most negative values come from the gabbro. Most rocks are enriched in iron, some extremely enriched; none represent primitive mantle melts. The range of Mg-numbers is the same in the gabbro and the leucogabbro. Plots of the Ni-content vs. the Mg-number are scattered, but there is a positive correlation between these two parameters. The primary mantle-normalized ratios between similar trace elements are normally strongly different from one. Values larger as well as smaller than one are found for the same ratio in different rocks. The rare earth elements are only weakly fractionated with small Eu anomalies, negative for the gabbros and positive for the leucogabbros. The primary magma of the Nordingrå gabbro-anorthosite is thought to have been derived from a mildly depleted mantle source. Variations in the degree of partial melting of a reasonably homogeneous enriched mantle do not explain the observed chemical evolution. Crystal differentiation can account for some geochemical features, especially the Fe-enrichment. Crustal contamination is required by other characteristics as, for example, the negative εNd(T) values and the irregular and sometimes high primary-mantle normalized incompatible trace-element ratios. Al-rich relic material from the formation of the rapakivi granite melt is another source of assimilation. Most probably contaminants are heterogeneous, including undepleted crust (represented, for example, by early Svecofennian and Archaean granitoids), depleted crust (restitic after rapakivi magma extraction), and to some degree the associated rapakivi magma itself. Significant parts of this crust should be Archaean in age.

Crust–mantle interaction in western Turkey: implications from Sr and Nd isotope geochemistry of Tertiary and Quaternary volcanics

1991 ◽  
Vol 128 (5) ◽  
pp. 417-435 ◽  
Author(s):  
N. Güleç
Keyword(s):  
Trace Element ◽  
Isotope Geochemistry ◽  
Major And Trace Elements ◽  
Crustal Material ◽  
Calc Alkaline ◽  
Western Turkey ◽  
Alkaline Rocks ◽  
Trace Element Chemistry ◽  
Depleted Mantle ◽  
Lower Crustal

AbstractThe isotopic composition of Sr and Nd together with the abundance data for major and trace elements are reported for Tertiary to Quaternary volcanics from a variety of localities in western Turkey. These data are used to evaluate the role of crust–mantle interaction in the petrogenesis of the western Turkish volcanics. The major and trace element chemistry reveals a general change in the nature of volcanism from dominantly calc-alkaline in Tertiary to alkaline in Quaternary times. The calc-alkaline rocks are quartz-normative and comprise andesitic to rhyolitic compositions of Miocene–Pliocene age; the trace element patterns are typical of continental margin volcanics with high Ba/Nb ratios and negative Ti anomalies. The alkaline rocks are nepheline-normative and dominantly Quaternary in age; they are basic in composition, with a change from potassic nature in Miocene–Pliocene to sodic in Quaternary times. Most of the Tertiary alkaline volcanics display trace element patterns similar to those of the calc-alkaline ones, whereas the Quaternary alkaline volcanics have low Ba/Nb ratios without negative Ti anomalies; they resemble intraplate volcanics.The calc-alkaline rocks have high87Sr/86Sr (from 0.705011 to 0.709529) and low143Nd/144Nd ratios (from 0.512294 to 0.512691). With the exception of two Tertiary samples, all the alkaline volcanics plot within the so-called mantle array of the isotope correlation diagram,87Sr/86Sr ratios ranging from 0.703128 to 0.703628 and143Nd/144Nd ratios ranging from 0.512749 to 0.512998. The two Tertiary alkaline samples, with trace element patterns similar to those of the calc-alkaline ones, have considerably higher Sr (0.707741–0.707918) and lower Nd (0.512494–0.512514) isotope compositions. The combined isotope and chemical data suggest the derivation of the western Turkish volcanics from variable mixtures of melts generated in two different mantle regions. The calc-alkaline volcanics were essentially derived from the continental lithospheric or shallow asthenospheric mantle which was contaminated with upper crustal material during earlier subduction events. The generation of the alkaline volcanics was controlled by melts derived from relatively deep, isotopically depleted mantle regions. Most of the volcanics were subjected to contamination at crustal levels, through the operation of an assimilation–fractional crystallization (AFC) process. The nature of contaminant changed from upper crustal in the calc-alkaline to lower crustal in the alkaline volcanics, accompanying the overall decrease in the amount of contamination from about 50% down to about 10%, and broadly paralleling the transition from compressional to extensional tectonics in the region.

Ultramafic rocks at the Isua supracrustal belt and East Pilbara Terrane are crustal cumulates, not slices of early mantle

2020 ◽  
Author(s):  
Jiawei Zuo ◽  
Alex Webb ◽  
Jason Harvey ◽  
Peter Haproff ◽  
Thomas Mueller ◽  
...  
Keyword(s):  
Trace Element ◽  
Plate Tectonics ◽  
Primitive Mantle ◽  
Geochemical Data ◽  
Ultramafic Rocks ◽  
Depleted Mantle ◽  
Supracrustal Belt ◽  
Element Fractionation ◽  
Trace Element Fractionation ◽  
Geochemical Studies

&lt;p&gt;The initiation of plate tectonics remains enigmatic, with the proposed onset timing ranging from Hadean to Proterozoic. Recently, many mineralogical, petrological and geochemical studies suggest onset of plate tectonics at ~3 Ga. For example, the geology of East Pilbara Terrane (~3.55 to 2.70 Ga; Australia) is widely interpreted as representing Paleoarchean non-plate tectonics, followed by plate tectonics after a ~3.2 Ga transition. In contrast, Isua supracrustal belt (3.85 to 3.55 Ga; Greenland) has been dominantly interpreted via plate tectonics. There, two ultramafic lenses have been interpreted as depleted mantle slices, emplaced via thrusting in an Eoarchean subduction zone, implying early plate tectonics. We present new petrological and geochemical data of ultramafic samples from the Isua lenses and from the East Pilbara Terrane to explore their origins. Pilbara samples appear to preserve cumulate textures; protolith textures of Isua samples are altered beyond recognition. Samples with low chemical alteration show similar whole-rock chemistry, including up to 5.0 wt.% Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; and up to 0.25 wt.% TiO&lt;sub&gt;2&lt;/sub&gt; that both covary negatively with MgO (37.1 to 47.5 wt.%); these variations suggest cogenetic relationships with local lavas. Flat trace-element fractionation trends parallel those of local lavas in the primitive-mantle normalized spider diagram. Spinel crystals from Pilbara samples yield ~20-60 Mg#, relatively constant Cr# at ~70, and 0.61-4.81 wt.% TiO&lt;sub&gt;2&lt;/sub&gt;. Our data are consistent with crustal cumulate emplacement. In contrast with depleted mantle rocks, our samples have higher whole-rock Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; and TiO&lt;sub&gt;2&lt;/sub&gt;, flat (vs. upward) trace-element fractionation trends from less to more compatible elements, and spinel crystals with higher TiO&lt;sub&gt;2&lt;/sub&gt; and relatively constant (vs. varied) Cr#. Therefore, Isua and Pilbara ultramafic rocks may have similar, non-plate tectonic origins, and the Isua record allows a ~3 Ga onset of plate tectonics.&lt;/p&gt;

scholarly journals Petrography and Geochemistry of Gabbroic Rock from the Penjwin Ophiolite, Kurdistan Region, Northeastern Iraq

2021 ◽  
Vol 54 (2E) ◽  
pp. 24-37
Author(s):  
Sarmad A Ali
Keyword(s):  
Rare Earth ◽  
Field Strength ◽  
Rare Earth Elements ◽  
High Field ◽  
Major Elements ◽  
Primitive Mantle ◽  
High Field Strength ◽  
Tholeiitic Magma ◽  
Depleted Mantle ◽  
Compositional Variations

The gabbroic rocks as a part of Zagros ophiolite are exposed in northeastern Iraq, Penjwin area. These rocks with granular to ophitic textures are widely distributed without metamorphic halos. The main minerals are plagioclase (An90-99), olivine, clinopyroxene (Wo27-47 En 45-64 Fs8-14) and orthopyroxene (Wo2 En78 Fs20) respectively based on the abundances. The major elements show a broad range of compositional variations, with SiO2 (46.2–50.9 wt. %), and low concentrations Na2O (0.15–0.62 wt. %), K2O (0.01–0.03 wt. %) and TiO2 (0.06–0.2) and high concentrations, Al2O3 (6.4–19.75 wt. %), total Fe2O3 (6.29–11.6 wt. %), MgO (9.63–24.5 wt. %), CaO (8.02–18 wt. %) and low alkali contents (Na2O + K2O = 0.16–0.65 wt. %). On Ti-V diagram, all of the gabbroic samples have Ti/V less than 10 and consequently fall in the low Ti- Island arc tholeiitic. Whole rocks chemistry shows a depletion of High field strength elements in comparison with the primitive mantle with an arched upward rare earth elements pattern, characterized by light rare earth elements depletion (La N/Sm N = 0.05–0.8) and enrichment in the High field strength elements. Whole rocks chemistry, mineral paragenesis and chemistry of these rocks are more consistent with tholeiitic magma series. Based on our findings in this research, the primary magma has been produced from the depleted mantle with a high degree of partial melting.

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